varibale as listeneres javascirpit
x = { aInternal: 10, aListener: function(val) {}, set a(val) { this.aInternal = val; this.aListener(val); }, get a() { return this.aInternal; }, registerListener: function(listener) { this.aListener = listener; } } Then you can register a listener using the following: x.registerListener(function(val) { alert("Someone changed the value of x.a to " + val); });
Source: stackoverflow.com